Technical Abstract:
Postchill whole carcass rinsing (WCR) and neck skin (NS) maceration are frequently used methods to detect Salmonella from commercially processed broilers in the U.S. and E.U., respectively. These are nondestructive, practical methods that may result in frequent false negatives. WCR will not detect firmly attached Salmonella and only 7.5% of the rinsate is utilized, while NS samples only 4% of the skin by weight of the broiler carcass. In 1975 a whole carcass enrichment (WCE) method was developed as a research tool. This involves incubation of the whole carcass overnight in a preenrichment broth and can recover as few as 8 inoculated Salmonella cells per carcass. The objective of this study was to compare NS, WCR, and WCE to detect naturally occurring Salmonella from the same commercially processed broiler carcass prechill or postchill. Ten carcasses were taken prechill and another 10 postchill on each of two replications from each of two processing plants. From each carcass, 8.3g of neck skin was sampled and then the carcass was rinsed with 400 mL of 1% buffered peptone water. Thirty mL were removed and incubated, and the remaining 370 mL of broth and the carcass were incubated at 37oC for 24 h. Overall Salmonella were detected on prechill carcasses 21/40 (52.5%), 24/40 (60%) and 32/40 (80%) with the NS, WCR, and WCE, respectively, while postchill carcasses were 2/40 (5%), 2/40 (5%) and 19/40 (47.5%) for NS, WCR and WCE, respectively. The 240 samples (40 carcasses X 3 methods X 2 plants), prechill were 77/120 (64.2%) positive while postchill were 23/120 (19.2%) positive. Chlorinated chilling reduced the positive sample prevalence by 45%. Salmonella were detected on 20% (24/120) of the samples from plant 1 and 63.3% (76/120) of the carcasses from plant 2. This study demonstrates differences in Salmonella prevalence among sampling methods, before and after chlorinated immersion chilling, and plant to plant.
Key words: Salmonella, broiler carcasses, sampling methods